The present invention generally relates to apparatus for controlling rotation of an input relative to an output, particularly relates to rotational control apparatus for use with servo-motors, and specifically relates to servo-motor brakes.
Servo-motors are increasingly being used as drives in the control of machinery component movement. There are servo-motor applications where it is desirable to stop movement of the machinery component being driven including but not limited to parking or emergency stop situations but also in the event of disruption of power to the servo-motor. Typically, servo-motors were purchased from manufacturers either with or without an integral braking component. However, a need has arisen for a brake to be added as a module separately to servo-motors. In particular, this would allow servo-motor users to purchase a standard servo-motor for all applications (assumedly at a lower per unit price due to quantity discounts) and then to add a brake module to the servo-motor only in applications where braking is needed or desired. In a preferred aspect, it would be desirable that such add on servo-motor brakes have performance characteristics which exceed those of integral servo-motor and brake units and which minimize the overall product size.
A major obstacle to satisfying this need is that the servo-motor industry has not adopted a standard configuration. In particular, the drive shafts of servo-motors are of different radial sizes. Also, although typically including a pilot on the output face, the sizes and shapes of pilot faces differ between manufacturers of servo-motors. Additionally, although typically the output face includes four bores which may be threaded and which were located at the corners of a square larger than the pilot and for receipt of screws extending from the apparatus component to be driven, such bores were of different diameters and were located at different radial spacings from the drive shaft. To reduce inventory requirements and to take advantage of mass production, it is desirable that brakes intended to be modules for attachment to servo-motors should have universal application to all servo-motors of whatever manufacturer and should be easily and readily modifiable to that of the particular servo-motor to which it is desired to be attached.